1. Field of the Invention
This invention relates to a kit for the construction of a pipe expansion joint, a pipe expansion joint and a system for anchoring traction elements of a flexible, tubular structure in the opening of a flange or rigid wall, in which the anchoring is caused by axial contact of a shoulder of the traction element with the flange or rigid wall after passage of the traction element through the opening made in the rigid wall. To simplify the description of the invention, the term "sleeve" will be used to define the flexible tubular structure, and the term "bead" will be used to define the extremity or traction device of the sleeve, which extremity has a diameter greater than the diameter of the sleeve, and which extremity makes contact with the rigid wall. The rigid wall will be designated by the term "counterflange".
2. Background Information
The known art includes sleeves having a flexible bead, in which the bead generally includes an internal armature that may be embedded in the material of the sleeve. This armature may be in the shape of a ring, and may consist of: rubber with a high modulus of elasticity, a strip of textile, a textile or metal strand or even a flexible spring. This type of reinforcement is adopted to make the bead deformable so that the bead can be forced through the smaller diameter hole of the counterflanges, to thus allow the counterflanges to be put onto the sleeve after the sleeve is fabricated. The major disadvantage of these systems is the necessity for pinching a flat counterflange between two planes, or in the use of a shaped counterflange, obtained by machining, so that a rigid part of the counterflange comes into contact against an inside diameter of this deformable bead as, for example, in the pneumatic suspension membranes described in French Patent No. 2 127 561 to Continental Gummi-Werke Aktiengesellschaft, or in the expansion compensation sleeves described in French Patents Nos. 2 280 853 to Barghofer, 2 033 789 to Pirelli Societa Per Azioni, or 2 006 730 to Continental Gummi-Werke Aktiengesellschaft.
These systems of sleeves, which have flexible beads, therefore require assembly techniques which frequently cause a high concentration of stresses at the extremity of the counterflange, which stresses can damage or even destroy the seal. Therefore, conventional sleeves with flexible beads can only be used for moderate service pressures. To eliminate these disadvantages, rigid beads having a large contact surface with the flange have been proposed. This is the solution adopted by Kleber Industrie for its integrated tube flanges, which it markets under the trade name Endlfex System (described in the Kleber Industrie Performer AD 10 Hose Catalogue, Page 4), or its Dilatoflex K expansion sleeves described in the Kleber Industrie Catalogue FC175-18, dated Jun. 1984. these devices all have a high rigidity and are most frequently made with metal components. As a result of their design, the rubber is compressed over a large contact surface, which improves the distribution of stresses and reduces the creep sensitivity of the rubber, thereby providing a better seal and allowing the device to be used at high service pressures.
On the other hand, on account of their rigidity, these beads have the disadvantage that they prevent the assembly of one-piece counterflanges to the sleeve after the sleeve is fabricated. It is therefore necessary to proceed with the assembly of the counterflanges to the sleeves during production of the sleeves, thus, making it necessary to vulcanize the sleeve after the sleeve is equipped with its metal parts, which metal parts add significantly to the weight and volume of the sleeve, thus making the sleeve more difficult to handle.
In addition, the counterflanges, when put on during the production of the sleeves, are no longer removable, as indicated by the Stenflex catalogue No. 2 of Jun. 1984, and the General Rubber corporation catalogue. The manufacturer or supplier of the sleeves must, therefore, maintain a large inventory of a wide variety of sleeves so that sleeves equipped with flanges, which flanges match all of the various standardized connections, are always available.
A sleeve with removable flanges is described in French Patent No. 2 447 512 to Rudolf Stender, but the beads are rigid and have reinforcement collars which are separate from the sleeve. The proposed solution, which consists of surrounding the collar with a U-shaped rubber piece, requires the realization of a very complex mold for the formation of the sleeve.
As a result of the above analysis, Caoutchouc Manufacture et Plastiques developed a sleeve in which the rigid armature constituting the shoulder becomes rigid after passage of the armature through the opening of the wall of the counterflange. The three patents, European Patent No. 0 196 954 to Roux et al., European Patent No. 0 202 131 to Bechu et al., and European Patent No. 0 207 813 to Bechu et al., have been issued for various features relating to this sleeve. The armatures of the sleeves described in these three patents can be fitted through the opening of the flange by bending the armatures in the axial direction of the sleeve. The armatures themselves can generally be constructed as one-piece armatures which can either be split mechanically or fragmented into smaller individual elements, or the armature may be constructed of individual elements which are connected to a flexible connection element.
These three variants describe an armature whose components differ from one another, but, which armatures, in each case, allow for bending of the armature in the axial direction, i.e., around convergent radial axes. In this operation, a number of sectors of the armature, i.e., two or three, are pressed back toward the rear of the sleeve, which allows the opposite sectors to be folded toward the front, until they are engaged in the hole of the counterflange. This operation, which is difficult to automate, but which has advantages such as a reduction in the size of the inventory of both counterflanges and sleeves of the various types which must be maintained, is necessary to meet the demand for a large variety of combinations. These armatures can even be used effectively on small-diameter sleeves, which, for the expansion joint industry, means nominal diameters of less than 400 mm of exposed cross section.